Self-contained rotary fuel pump

ABSTRACT

An electric fuel pump which is self-contained in a unitary housing with a fuel inlet at one end leading to a rotary eccentric pump, the pumped fuel passing out an outlet at the other end of the housing. A relief valve in the form of a shaped plate at the pump end bypasses fuel when there is reduced demand at the outlet. The outlet end of the pump is formed as a brush holder for the electric drive motor and a magnet retainer for the field assembly. A self-aligning composite pump assembly is utilized with a motor housing. A substantially constant pressure at the outlet with varying outlet flow is the function of the relief valve.

This application is a division of my copending application, Ser. No.123,103, filed Feb. 19, 1980, now U.S. Pat. No. 4,352,641, issued Oct.5, 1982.

FIELD OF INVENTION

The invention is directed to fuel pumps for internal combustion enginesand particularly to pumps useful on automotive vehicles to furnish fuelfrom the gasoline tank to the engine in response to demands of theengine.

REFERENCE TO RELATED APPLICATIONS:

Reference is made to my copending application, Ser. No. 228,346, filedJan. 26, 1981, now U.S. Pat. No. 4,401,416, issued Aug. 30, 1983,entitled "Self-Contained Rotary Fuel Pump," which is acontinuation-in-part of application, Ser. No. 123,102 (now abandoned),filed Feb. 19, 1980.

BACKGROUND OF THE INVENTION

Automotive vehicles have used gravity feed for fuel in the early stagesof the industry and the next phase beyond this was a diaphragm pump inwhich the diaphragm was mechanically pulsed by a lever actuated by a camactuated by the engine itself. Also, electric pumps have been used withthe pumping action provided by a solenoid armature reciprocating in asolenoid winding in response to electrical contacts in a circuitresponsive to the motion of the armature.

In every case there is a problem of matching the fuel supply to thedemand of the engine under all conditions of operation, whether it beidling, full open throttle at high speed, or open throttle under loadsuch as climbing a hill or moving through sand or snow where the loadcauses a reduced speed even with open throttle.

It is also important to have a fuel pump which will have a reliableoutput under all conditions of ambient temperature in winter and summer.

It is an object of the present invention to provide a constant speedrotary electric pump which can yet respond to fuel demand by theoperation of a unique relief or by-pass valve at the rotary pump inlet.A further object is a rotary pump design which has a steady, even outputflow with minimal surging in the output so the engine fuel mixing devicecan perform its function unaffected by a surging fuel supply.

Another object is a pump design which is compact and of a size to beeasily mounted in a safe area in an automotive vehicle. It can bemounted in or out of the fuel tank.

Another object is to provide a unit wherein the pump assemblyautomatically aligns itself to the motor shaft, thus preventing frictionor binding due to misalignment.

Other objects include providing a pump relief system which can provide asubstantially constant pmp outlet pressure even though the outlet flowmay vary from the maximum desired flow to a minimum flow.

The pump incorporates a simple pressure regulator valve in conjunctionwith pulse adsorption devices to provide a smooth flow of fuel. Thepressure relief valve is designed for an initial lift-off in response topump pressure and automatically expose additional area to the pressureto steady the by-pass and avoid an erratic or jerky "hunting" for thedesired pressure. Attention is directed to U.S. Pat. Nos. to Catterson,3,415,195, dated Dec. 10, 1968, and O'Connor, 3,470,824, dated Oct. 10,1969, where a magnetic relief valve plate is utilized in connection witha rotary fuel pump.

A further object is the provision of a retainer shell which holds therespective parts together under resilient compression in a sealedrelationship.

A further object of the invention is the provision of a pump shaftbearing at the outlet end of the pump assembly and a pump housingretainer shoulder at the pump end cooperating with a spherical annularsurface to permit pump shaft alignment without binding forces on theshaft.

A further object is the provision of a rotary pump housing with anoutlet end plate and bearing pressfitted therein to a properrelationship with the pump rotor, thus avoiding expensive machiningoperation to obtain a proper fit. A resiliently biased relief plate withannular pockets for exposure to pump outlet pressure is provided at theinlet end of the pump in the form of a thin metal disc with annularpressure ridges disposed in a common plane.

Other objects and features of the invention will be found in thefollowing description and claims in which the principles of theinvention are set forth, together with a detailed description and partswhich make up the operating assembly, all in connection with the bestmodes presently contemplated for the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS:

DRAWINGS accompany the disclosure, and the various views thereof may bebriefly described as:

FIG. 1, a longitudinal sectional view of an assembled pump constructedin accordance with the invention.

FIG. 2, a partial section of the outlet end of the pump at 90° to theshowing in FIG. 1.

FIG. 3, an elevational view of a pump rotor.

FIG. 4, an elevation view of an end plate for a pump.

FIG. 5, a sectional view of a relief valve plate.

FIG. 6, an elevation of the relief valve plate shown in FIG. 5.

FIG. 7, a sectional view on line 7--7 of FIG. 1 showing the magnetassembly and retainers.

FIG. 8, a view from the top of FIG. 7 with some parts deleted forclarity.

DESCRIPTION OF THE INVENTION AND THE MANNER AND PROCESS OF MAKING ANDUSING THE INVENTION

WITH REFERENCE TO THE DRAWINGS, FIG. 1 illustrates the assembled partswhich, from left to right, include an inlet cap 20, a cylindrical pumphousing 22 with a stepped bore, and an outlet end housing 24 whichhouses an armature assembly, brushes and the like to be described. Theseparts are housed in a metallic shell 30 flanged at 32 to retain theinlet end 20 and flanged at 34 at the other end around a compressibleO-ring 36 which bears against a shoulder on outlet end housing 24.

The outlet end 24 of the assembly carries an armature 40 and brush plateassembly mounted at one end on the motor shaft 42 which has a left-handend 44 for driving a pump rotor. A spherical bearing element 46 aroundshaft 42 seats in a conical recess 48 and is retained by a resilientmetallic retainer plate 50 pressed into a recess in housing 24 against ashoulder 52. Brushes 54 and 56 are slidable in retainer sleeves 58 andurged against a commutator plate 60 by coil springs 62. The brushretainers are conductors which have extending terminals 64 and 66. Anappropriate pair of arcuate magnetic flux elements 67 (FIG. 7) areretained by spring clips 68 and are disposed around the armature 40retained between axial arms 70 of end housing 24 and within a flux ring71 inside the shell 30. The axial arms 70, shown in plan, in FIG. 8 aresplit into flexible fingers 70a and the Jshaped spring members 68 tendto spread these fingers apart and cause them to bear on the ends of thearcuate flux members to hold them out against the flux ring 71.

With reference to FIG. 2, which is a section at 90° to that of FIG. 1, apump outlet port 72 opens to a bore 74 which supports an outlet nippletube 76. A valve seat at the juncture of port 72 and bore 74 cooperateswith a valve member 78 urged against the seat by a spring 80. The outletpressure of the pump must unseat this valve which closes to contain fuelin the pump in the event of a power loss or engine shut-off if used inan automotive vehicle. This valve also retains fuel in the event of anaccident which results in overturn of a vehicle.

The spherical bearing 46 around the shaft 42 has a function in thearmature shaft alignment as will be described below.

Turning now to the pumping structure, shown in FIGS. 1 and 3 to 6, theinlet end cap 20 has a connector nipple 90 surrounding an inlet port 92.The inner surface of end cap 20 has a bore 94 enlarged from port 92 toform a shoulder 96 which serves as a seat for one end of a coil spring98. Radial slots 100 provide fuel passages for incoming fuel and theintervening ribs strengthen the end cap. An O-ring or other suitablepacking ring 102 is interposed between end cap 20 and housing member 22and retained under resilient compression by flange 32 of shell 30.

Cylindrical housing 22 has a first bore 110 which carries an outercircumferential pump housing or cam ring 112 in which rotates pump rotor114 driven by a key-slot engagement on end 44 of motor shaft 42. Theelevation profile of rotor 114 is shown in FIG. 3, there beingcircumferentially spaced radial slots 116 opening to the periphery tocarry rollers 120 which serve as pump vanes, these being held outagainst the outer periphery of the eccentric recess 122 in cam ring 112by centrifugal force.

The right-hand end of the cam ring 112 has an annular enlargement 124with a surface 126 which is preferably spherical. This surface bearsagainst a corner of a shoulder 127. There is sufficient clearancebetween cam ring 112 and the bore 110 to permit the ring to rock aroundthe shoulder 127. Thus, with the spherical bearing 46 as a support forthe right end of shaft 42, the entire assembly including the cam ring112 can adjust to an alignment condition during assembly so there is nobinding or bending of the shaft 42 by misalignment.

The end 44 of shaft 42 operates in a bearing collar or bushing 130 whichhas a flange 132 in recess 122 to close one end of the circumferentialhousing 112 and to serve as the back-up cover plate for the pump rotor.A thrust washer 134 is provided for the armature shaft.

In assembly, this bearing collar 130 is pressed into the cam ring recess122 so that the flange 132 is moved to a gauged position where it hasexactly the right axial clearance for the pump rotor 114, in otherwords, a "press fit". Webster's International Dictionary, SecondEdition, 1950, defines a "press fit" as a force fit. The MetalsHandbook, 8th Ed. of American Society for Metals, 1961, defines "pressfit" as "an interference or force fit through the use of a press." Thefit between the collar and the cam ring is such that this position willbe stable in operation. Thus, expensive machining is avoided by thisconstruction and assembly.

To the right of the cam ring is a pulse dampener ring in the form of aring 140 of closed cellular material resistant to hydrocarbons supportedbetween retainers 142 and 144, the latter shell being pressed in againstshoulder 146. A relatively heavy coil spring 150 presses against theshell 142 to urge the pump assembly to the left against the shoulder127.

The end of the pump opposed to flange 132 is composed of a closureassembly which also serves as a relief valve to by-pass fluid undercertain conditions of operation. An aluminum disc 160 with an opencenter hole 162 (FIG. 4) enlarged to a segmental slot 164 bears againstthe inlet end of cam ring 112 and the rotor 114. A pin 166 anchored inring 112 passes through a notch 168 in disc 160 to providecircumferential orientation. To the left of this disc 160 is a pressureregulating valve plate 170, shown in FIGS. 5 and 6, which has as shallowcentral cup 172 serving as a retainer for coil spring 98 which urges theplate 170 toward the disc 160. The plate 170 is formed of stainlesssteel approximately 0.010 to 0.030" thick, and has an outer flange 174with a 15° inwardly tapering annular portion 176 from face plane A--A, areturn portion 178 to the face plane A--A, a second annular taperedportion 180 disposed at about 25° to the face plane A--A with a return182 which forms the wall of cup 172. The base of the cup is spaced fromthe face plane A--A. Four small holes 183 (0.052-0.055" diameter) arelocated on diameters normal to each other. The diameter of the plate inthis particular example is 2.455" but the invention is not limited to aparticular dimension.

It will be seen that the above-described relief plate has two radiusedannular surfaces 184 and 186 (FIG. 5) which touch the face plane A--A.

Interposed between plate 170 and disc 160 is a pressure regulating seal188 in the form of a flat ring of thin resilient material, buna N, orother hydrocarbon resistant resilient material which is open at thecenter and has a radial span to overlie the annular surfaces 184 and186.

It will be noted that there are axial passages 109 in the periphery ofbore 110 in housing 22, shown in dotted lines, which align with the wallof the end cap 20 to carry inlet fluid through radial passages 169 tothe periphery of the pump rotor 114. Also passages 190 in flange 132(dotted lines) in FIG. 1 provide outlet for the pump rotor. Thesegmental opening 164 in disc 160 (FIG. 4) is aligned with the outletport 190. A pulse dampener ring 200 is also positioned behind plate 170formed of a cellular material, closed-cell type.

IN THE OPERATION

A fuel supply connected to nipple 90 furnishes fuel to port 92 where thefuel passes through radial slots 100 to the passages 109 and throughpassages 169 which serve as the pump inlet. Fuel flows out of the rotorthrough passages 190 where it flows through the armature assembly to theoutlet end of end housing 24, through axial passages 200 (FIG. 2),around retainer plate 50 to the outlet passage 72, safety check valve78, and outlet 76. The vane pump rotor and vanes operate in a mannerwell known in the vane pump art.

Should the pressure build up to a predetermined point in the pump outletas established by the user, it will be reflected through segmentalopening 164 in disc 160 to the relief plate 170 backed by spring 98. Theresilient ring 188 serves to seal the annular surfaces 184 and 186against disc 160. Upon the build up of a certain pump outlet pressure,the fluid will pass annular surface 186 into the annular space insidethe annular surface 184 at the outer rim. Holes 183 will admit thisby-passed fluid to the inlet side of the pump, and it will continue tobypass until the outlet pressure drops to the desired setting. Spring 98will control this by-pass pressure. Holes 183 are calibrated to relievea predetermined pressure but pressure can also by pass under annular rim184 and the combination of these holes plus the spring pressure enablesreasonably accurate control of pump outlet pressure regardless of outletflow demand.

With respect to the overall pump assembly, it will be noted that theinlet and outlet caps 20 and 24 together with the pump surround 22 andthe motor flux ring 71 are held in axial assembly by the shell 30, theflanged ends 32, 34 of which lock the parts under resilient bias ofsealing rings 36 and 102.

I claim:
 1. A pump body for a rotary fuel pump having an inlet end andan outlet end in which said inlet end comprises a first end plate on theinlet end of the pump, a circumferential housing having a pumpingchamber closed at the inlet end by said first end plate, an outlet platepressed into said chamber of said circumferential housing having a faceto lie perpendicular to the axis of said housing, said outlet platebeing positioned axially by way of a press fit into said pumping chamberof said circumferential housing to a position fixed in the housing toprovide a pumping chamber with a fixed predetermined axial dimension,and a rotor in said pumping chamber between said first end plate andsaid face of said outlet plate with predetermined axial clearance forrotation in the pumping chamber thus formed within said circumferentialhousing.